A phenomenon I've noticed since I've become published is of serious, talented, and/or accomplished writers (both published and unpublished) who are terrified at the idea of writing a novel.
The fear of writing a novel is understandable. Writing a novel is nontrivial.
There are, I think, several aspects to this angst. First off, of course, is the classic tyranny of the empty page -- and it doesn't get emptier than the yawning chasm of a ream of empty sheets in your laser printer, especially nowadays with Microsoft and that annoying paper clip icon thing. Second, I think, is that you as a novelist do in fact "put yourself out there" emotionally to a degree other writers do not necessarily experience. (I've also found that a lot of people assume that you are at least one of the characters in your novel, which is somewhat true of all your characters; not to the degree assumed perhaps, but also somewhat unnerving.). You will encounter both of these terrors each time you sit down to write a novel.
But the conclusion I've reached is this: Novel writing involves making a multitude of decisions. The hardest thing in life, no matter what aspect, is to make a decision. Period. Think about it. You will angst over an important decision in your life: Whether to get married; whether to break up; when to ask him/her out; whether you should take that job; whether you should tell your best friend that person is not for him/her; whether you should buy that house, make that investment; whether and how you should discipline your child; whether you should break the rules; etc. The ghastly 1980s drama "thirtysomething" (you can't even find it on "Television without Pity") was enormously successful making much out of angsting over the trivial (Apple Jacks or Count Chocula?!).
But, here's the thing [John Tesh moment]: once you actually make the deicison, things are better. You simply have to deal with what comes. You don't have to imagine the consequences of what might have been, because something will be.
Guess what? Novel writing is all about that infinite tryanny of possibilities. When you write a novel, you can do anything. The question is, what? My advice is to pick one of the myriad of options, no matter what, definitely make a note of the possiblities you've rejected, and get on with it. Write. If it doesn't work, you can come back to it later. Always.
Also, if worse comes to worst, remember the words of Theodore Roosevelt:
"In the battle of life, it is not the critic who counts; nor the one who points out how the strong person stumbled, or where the doer of a deed could have done better.
"The credit belongs to the person who is actually in the arena; whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again, because there is no effort without error and shortcoming; who does actually strive to do deeds; who knows the great enthusiasms, the great devotion, spends oneself in a worthy cause; who at the best knows in the end the triumph of high achievement; and who at worst, if he or she fails, at least fails while daring greatly.
Far better it is to dare mighty things, to win glorious triumphs even though checkered by failure, than to rank with those timid spirits who neither enjoy nor suffer much because they live in the gray twilight that knows neither victory nor defeat."